Digital still imaging devices, such as digital still cameras (“DSCs”) and mobile telephones that include imaging devices (“camera phones”) often need auxiliary lighting, such as from a flash module, when taking pictures in low-light conditions. DSCs and camera phones often have a built-in flash module for this purpose. It is generally desirable that the flash module produce light within the viewing angle of the camera to uniformly illuminate the object of the picture.
Different types of light sources are used to produce light for the flash. White light is generally desired to achieve good color in the image. Gas discharge tubes are one type of light source used in flash applications. Light-emitting diodes (“LEDs”) are another type of light source used in flash applications. LED chips produce essentially a single color (wavelength) of light. A “white LED” is obtained by using wavelength-converting materials to convert light from an LED chip to different wavelengths, and the combination of lights from LED chip plus wavelength-converting materials will produce white light.
Auxiliary lighting is also used in some DSCs to assist in auto-focusing the device on the object before the picture is taken. A separate LED is provided for this purpose, and is commonly referred to as an “auto focus auxiliary LED (“AFA LED”). An AFA LED typically produces high brightness through a narrow viewing angle, as opposed to a flash module, which produces light through a relatively broad viewing angle, and is separate from the flash source.
FIG. 1A shows a prior art DSC 100 having an AFA LED 102 and a flash module 104. The flash module is a non-LED light source, such as a gas discharge tube. There is sufficient area on the face of the DSC 100 to put both the AFA and flash light sources; however, it is difficult to accommodate both light sources on smaller digital imaging devices, such as smaller DSCs and camera phones. AFA LEDs are often omitted from camera phones, which affects their auto-focus function, particularly in low-light conditions. It is desirable to provide an auto-focus auxiliary light that avoids the problems described above.